Wireless power transmission technology denotes technology that transmits power without using a wire. Transmitting power without a wire is like a magic, but wireless communication technology is being currently used. When the wireless power transmission technology is realized, the ripple effect is very great, and thus, the wireless power transmission technology is attracting much interest. If power of tens W or more is wirelessly supplied, a paradigm of information technology (IT) is expected to be innovatively changed.
In particular, portable IT equipment that is a core of wireless communication technology freely performs wireless communication over a network such as a mobile communication network, a wireless local area network (LAN), or the like. However, the portable IT equipment is supplied with power from a charged battery, and thus, interest in realizing a wireless device is inevitably high. To date, the wireless power transmission technology has been developed, but only a contactless induction coupling scheme has been commercialized.
For example, some research for using a microwave was done in the past so as to transmit high power of tens W or more, but is not actively commercialized due to an influence of the microwave on a human body and straightness based on the use of a high-efficiency antenna. However, high power wireless transmission technology based on a non-radiated scheme, proposed by Marin Soljacic professor team of a physics department of MIT university in 2007, transmits high power of 60 W at a distance of 2 m by using a carrier wave of 10 MHz, and thus is attracting much attention as future promising technology.
In a related art smartkey system, a smartkey electronic control unit (ECU) drives a low frequency (LF) antenna by using an antenna driving IC, and a fob receives a request signal transmitted through the LF antenna to check the request signal, and transmits an identification (ID) in response to the request signal. When a radio frequency (RF) receiver receives the ID, the smartkey ECU determines the received ID as an ID of a vehicle fob to allow a vehicle to start.
When a battery of the fob is discharged, the smartkey ECU drives a base station IC to drive an LF antenna for transponder (TP) communication, and by performing the TP communication with the vehicle fob, the smartkey ECU determines a corresponding ID to allow a vehicle to start.
In the related art, a smartkey system drives an LF antenna to search for a fob, for starting a vehicle, and when a corresponding ID is checked, the smartkey system allows the vehicle to start. Here, the LF antenna uses a frequency of 125 KHz.
Recently, a wireless charging system is equipped in a lot of vehicles, and a frequency that is used for charging in a wireless charger is within the same band as that of a frequency that is used to search for a fob through LF communication. For this reason, frequencies overlap, causing a malfunction.